Bay 12 Games Forum

Please login or register.

Login with username, password and session length
Advanced search  
Pages: 1 ... 127 128 [129] 130 131 ... 173

Author Topic: Mathematics Help Thread  (Read 226945 times)

bahihs

  • Bay Watcher
    • View Profile
Re: Mathematics Help Thread
« Reply #1920 on: October 13, 2015, 07:25:31 pm »

Can someone please help me with the stat question I posted? The test in two days and I'm getting worried.
Logged

Spehss _

  • Bay Watcher
  • full of stars
    • View Profile
Re: Mathematics Help Thread
« Reply #1921 on: October 13, 2015, 07:56:28 pm »

Can someone please help me with the stat question I posted? The test in two days and I'm getting worried.
I'd help if I was familiar with statistics. That's "stat", right?
Logged
Steam ID: Spehss Cat
Turns out you can seriously not notice how deep into this shit you went until you get out.

Reelya

  • Bay Watcher
    • View Profile
Re: Mathematics Help Thread
« Reply #1922 on: October 13, 2015, 07:56:45 pm »

Am I doing things right? And where did the dy/dx come from between steps 2 and 3 in part A? I don't give a shit how efficiently I could've done it or what other methods there are to solve the problem, I want to know if I'm doing the "implicit differentiations" shit right.

The added dy/dx was needed because the differential where (y^2) = 2y is actually y^2 differentiated with respect to y, not x. So I'm guessing it's actually d(y^2)/dy * dy/dx to cast it into a differential with respect to x, not y. Note that there are a dy on the top and bottom, which "cancel out" according to the slightly arcane rules of calculus.
« Last Edit: October 13, 2015, 08:02:13 pm by Reelya »
Logged

Spehss _

  • Bay Watcher
  • full of stars
    • View Profile
Re: Mathematics Help Thread
« Reply #1923 on: October 13, 2015, 08:06:29 pm »

The added dy/dx was needed because the differential where (y^2) = 2y is actually y^2 differentiated with respect to y, not x. So I'm guessing it's actually d(y^2)/dy * dy/dx to cast it into a differential with respect to x, not y. Note that there are a dy on the top and bottom, which "cancel out" according to the slightly arcane rules of calculus.

If it was d(y^2)/dy, wouldn't the result just be 2, not 2y? d(x)/dx is just 1, for example.
Logged
Steam ID: Spehss Cat
Turns out you can seriously not notice how deep into this shit you went until you get out.

Reelya

  • Bay Watcher
    • View Profile
Re: Mathematics Help Thread
« Reply #1924 on: October 13, 2015, 08:07:12 pm »

but it's y-squared not y.

Spehss _

  • Bay Watcher
  • full of stars
    • View Profile
Re: Mathematics Help Thread
« Reply #1925 on: October 13, 2015, 08:11:20 pm »

but it's y-squared not y.
...Right. 2y is not y^2. Probably should've thought more before posting that.
Logged
Steam ID: Spehss Cat
Turns out you can seriously not notice how deep into this shit you went until you get out.

MagmaMcFry

  • Bay Watcher
  • [EXISTS]
    • View Profile
Re: Mathematics Help Thread
« Reply #1926 on: October 13, 2015, 08:17:33 pm »

Spehss_?
Please stop scaring me.
:P
Spoiler: *eldritch noises* (click to show/hide)
Yes, this is actually maths. I actually need to condense half a book's worth of this stuff into a bachelor's thesis.
Logged

bahihs

  • Bay Watcher
    • View Profile
Re: Mathematics Help Thread
« Reply #1927 on: October 13, 2015, 09:48:42 pm »

Can someone please help me with the stat question I posted? The test in two days and I'm getting worried.
I'd help if I was familiar with statistics. That's "stat", right?

Indeed it is, Bayesian Statistics to be specific
Logged

Spehss _

  • Bay Watcher
  • full of stars
    • View Profile
Re: Mathematics Help Thread
« Reply #1928 on: October 14, 2015, 01:01:07 pm »

Assuming I did this right, solving for dy/dx using implicit differentiation for x^(3)+y^(3)=1 then y'=(-3x^(2))/(3y^(2)).

Right? This seems way simpler than the example I worked through yesterday. Makes me think I'm doing it wrong.
Logged
Steam ID: Spehss Cat
Turns out you can seriously not notice how deep into this shit you went until you get out.

Arx

  • Bay Watcher
  • Iron within, iron without.
    • View Profile
    • Art!
Re: Mathematics Help Thread
« Reply #1929 on: October 14, 2015, 01:05:56 pm »

Insofar as the forum makes it easy to read, I believe you are correct.

x3+y3 = 1
∴ y' = (3x2)/(3y2)

Yes?

Pseudoedit: Also what Ispil said. Markers tend to be anal about simplification at this level of calc.
Logged

I am on Discord as Arx#2415.
Hail to the mind of man! / Fire in the sky
I've been waiting for you / On this day we die.

Spehss _

  • Bay Watcher
  • full of stars
    • View Profile
Re: Mathematics Help Thread
« Reply #1930 on: October 14, 2015, 01:28:48 pm »

So I'm still not sure where y' fits in when solving implicit differentiations.

Working out one problem. Find y' of x²y²+xsiny=4.

I've found the derivatives of both sides of the equation, so it's currently 2x²y+2xy²+xcosy+siny=0. So now I solve for y'. But I'm not sure where y' is supposed to be included in that equation. Before this problem I figured y' would be multiplied with the y variable, and all the past problems worked out fine. But in this case that doesn't work because there's multiple instances of y variables.
Logged
Steam ID: Spehss Cat
Turns out you can seriously not notice how deep into this shit you went until you get out.

Arx

  • Bay Watcher
  • Iron within, iron without.
    • View Profile
    • Art!
Re: Mathematics Help Thread
« Reply #1931 on: October 14, 2015, 01:32:13 pm »

It's the same as before, you just have to do the same thing for every instance of y (so, 2(x2y)dy/dx etc).
Logged

I am on Discord as Arx#2415.
Hail to the mind of man! / Fire in the sky
I've been waiting for you / On this day we die.

Spehss _

  • Bay Watcher
  • full of stars
    • View Profile
Re: Mathematics Help Thread
« Reply #1932 on: October 14, 2015, 01:44:15 pm »

Every time you take the derivative of y itself, multiply by a y' (think about it; you took the derivative of y, which is y', so multiply by y' to show this). Then get everything that doesn't have y' on the right side, everything with a y' on the left side, factor out y', and divide.

So it'd be 2x²y(y')+2xy²+xcosy(y')+siny=0 because of using y' in the derivative of x²y² and using y' in the derivative of sin(y)?
Logged
Steam ID: Spehss Cat
Turns out you can seriously not notice how deep into this shit you went until you get out.

Arx

  • Bay Watcher
  • Iron within, iron without.
    • View Profile
    • Art!
Re: Mathematics Help Thread
« Reply #1933 on: October 14, 2015, 02:09:24 pm »

That looks right, assuming your trig derivatives are all kosher (which appears to be the case).
Logged

I am on Discord as Arx#2415.
Hail to the mind of man! / Fire in the sky
I've been waiting for you / On this day we die.

frostshotgg

  • Bay Watcher
  • It was a ruse
    • View Profile
Re: Mathematics Help Thread
« Reply #1934 on: October 14, 2015, 03:38:44 pm »

Pseudoedit: Also what Ispil said. Markers tend to be anal about simplification at this level of calc.
My experience is the opposite. Once you get to calculus, it's all about the process, not about algebra. Usually if your answer is an unsimplified form, they'll accept it. The answer is only 1 point anyways.
Logged
Pages: 1 ... 127 128 [129] 130 131 ... 173